1. Field of the Invention
The present invention generally relates to a socket connector, and in particular to a socket connector having ball grid array (BGA) contacts of which solder balls are effectively prevented from breaking due to different thermal expansions of the connector and a circuit board on which the connector is mounted.
2. The Prior Art
A socket connector connects an electronic device, such as a central processing unit module, to a circuit board. A ball grid array (BGA) configuration facilitates mounting the socket connector to a main circuit board. FIG. 1 of the attached drawings shows a portion of a conventional socket connector having BGA contacts. The socket connector comprises an insulative header 82 defining a plurality of through holes 820. Each through hole 820 receives a conductive pin 81 therein. The conductive pin 81 comprises a retention section 811 from which two opposite barbs 813 extend for engaging with side walls of the hole 820 thereby securing the pin 81 in the header 82. A soldering section 812 extends from the retention section 811 to which a solder ball 83 is attached. The solder ball 83 projects beyond a bottom surface of the header 82 for being soldered to a circuit board 9 to fix the connector thereto and establish electrical connection therewith.
Since the circuit board 9 and the header 82 are made of different material having different thermal expansion coefficients, when the solder balls 83 are soldered to the circuit board 9, the difference in expansion between the header 82 and the circuit board 9 may cause excessive strain in the solder balls 83 and eventually rupture the solder balls 83.
Furthermore, the pin 81 is soldered to the circuit board 9 with a very limited surface area resulting in a mechanically weak connection between the pin 81 and the circuit board 9. Furthermore, the pin 81 is made of a thin plate whereby the pin 81 is mechanically weak when resisting bending in a direction normal to the plate.
Thus, it is desired to provide a connector that eliminates the problems discussed above.